1. Field
The present application relates to a magnetoresistance element with a Heusler alloy as the magnetic layer, capable of increasing a plateau magnetic field Hp1 while maintaining a high (RA.
2. Description of the Related art
The patent documents described below disclose a CPP magnetic detection device in which current flows in a direction perpendicular to a film surface of each layer constituting multi-layers (for example, see [0027], etc of JP-A-2004-146480).
In the patent documents, a Heusler alloy is used in at least one layer of a free magnetic layer and a fixed magnetic layer (both layers all are described as a term of a ferromagnetic layer in JP-A-2004-146480) disclosed (see claim 2 of JP-A-2004-146480, claim 9 of JP-A-2004-214251, and claim 10 of JP-A-2005-116703).
A spin polarizability may improve more when the free magnetic layer and the fixed magnetic layer are formed of the Heusler alloy, than when the free magnetic layer and the fixed magnetic layer are formed of a CoFe alloy or a NiFe alloy. The improved polarizability leads to an increased magnetoresistance variation ΔR. In a CPP magnetic detection device, the product ΔRA of the magnetoresistance variation ΔR and an element area A is a very important parameter for improving a high record density. Accordingly, it is preferable that the Heusler alloy is used in the free magnetic layer or the fixed magnetic layer.
In one embodiment, besides the ΔRA, a plateau magnetic field is also an important parameter.
The plateau magnetic field Hp1 refers to a strength of an exterior magnetic field, when an exterior magnetic field is applied in a direction antiparallel to magnetization direction of the fixed magnetic layer and the magnetization in the fixed magnetic layer begins to reverse due to the exterior magnetic field.
The more intense the plateau magnetic field is, the steadier the magnetization direction of the fixed magnetic layer remains. Accordingly, a producing property can improve.
In the above patent documents, other Heusler alloys, which several have different compositions, are exemplified, but Co2MnGe or Co2MnSi having a high spin polarizability has been considered to be an appropriate material for the fixed magnetic layer or the free magnetic layer.
However, when Co2MnGe or Co2MnSi is used in the fixed magnetic layer and the free magnetic layer, the plateau magnetic field Hp1 may not be properly intense.
Additionally, the plateau magnetic field Hp1 is not described and even not mentioned at all in the prior arts described above.